This invention is based upon annular ring field relay optical systems, also referred to as "restricted off-axis field" optical systems. Examples of such systems are disclosed in U.S. Pat. Nos. 3,748,015 and 4,293,186 of Offner. The basic concept of such a system is employed in the present invention but with the addition of magnification. Two basic versions are described and claimed. One is a fully catoptric system which is usable where a high degree of image quality is not a factor. The other is a catadioptric system wherein the lenses are of fused silica and thus usable in the ultraviolet.
One version of the catoptric system will be described and two specific examples of a catadioptric system will be given.